1. Field of the Invention
The present invention relates to ceramics having nonlinear voltage characteristics.
2. Description of the Prior Art
Ceramics having nonlinear voltage characteristics which are made by a process in which zinc oxide is used as a main component and various elements are added thereto as subcomponents, in elemental form or as a compound thereof, are well known. These ceramics, which have a high nonlinearity factor, have been used as surge voltage absorbers or as constant voltage regulating elements.
A current (I) flowing through a nonlinear voltage element at the time of the application of a voltage (V) can be approximated by the following equation: EQU I = (V/C).sup..alpha.
wherein (C) corresponds to the voltate per mm of the element when the current density is equal to 1 mA/cm.sup.2, and (.alpha.) is the nonlinearity factor of the voltage. It is desirable for (C) to be selected at a suitable value depending on the conditions of use of the nonlinear voltage element, and for (.alpha.) to be selected to have the largest possible value.